1. Technical Field
The present invention pertains to a system and corresponding methods for removing contaminants from a contaminated air stream. In particular, the present invention pertains to a method and apparatus for enhancing the exposure of a contaminated air stream to germicidal radiation to optimize removal of contaminants from that air stream.
2. Discussion of Related Art
Currently, there are numerous devices utilizing ozone, generated by ultraviolet (UV) radiation of air, to sanitize air in a treated space (i.e., typically a room). Many of these devices generate large amounts of ozone gas to facilitate sterilizing of the air. Since ozone concentration levels required for sterilization are sufficiently high to be dangerous to people and/or animals, the use of these devices is typically limited to deodorizers for odors for which removal is difficult (i.e., smoke from fires, organic material spilled on clothing, etc.). Further, when such ozone devices are used in the proximity of people and/or animals, health authorities require that ozone concentrations be reduced to safe levels. However, these reduced or “safe” levels tend to be too low to effectively deodorize and clean air, thereby rendering the ozone approach undesirable.
Some devices utilize the germicidal qualities of ultraviolet radiation in a particular frequency range to destroy bacteria in the air, but generally either expose the treated space to high levels of radiation, thereby posing health risks to people and/or animals, (such as eye trauma and skin lesions), or use very low levels of radiation requiring low air flow rates to permit the air to be exposed to the radiation in the device over long exposure times. Long exposure times render the devices inefficient in that they lengthen the “turnover” time of room air (i.e., the time required to treat an entire room with the germicidal radiation). It is evident that long turnover times minimize the effectiveness of the device in that the room air can be re-contaminated before the device is able to sanitize all of the air in the room.
Inefficiency and ineffectiveness in prior art UV room air sanitizers are also caused by not properly mixing the air flowing through the device. In this regard, prior art devices typically utilize, and even strive for, laminar air flow through those devices. This limits the effect of exposure to UV radiation to the portions of the laminar flow closest to the UV bulb. In this regard, designers of prior art devices show little or no recognition of the decrease in UV radiation intensity as a function of distance from the UV source. It is desirable, therefore, to maximize proximity of the entire flowing air stream to the UV source. Apart from the laminarity of the air flow, other flow parameters, not considered in the prior art, must be addressed to optimize the exposure of the air to UV radiation in an air purifier to maximize the purification or “killing” effects of the radiation.
Changing UV source bulbs in prior art room sanitizers presents numerous problems, not the least of which is danger to the consumer should the difficult-to-access UV bulb break during the removal or insertion process. It is desirable to provide an efficient air purifier wherein the UV radiation source is readily and safely replaced.